Treads are required to have different properties such as rubber properties (e.g. fuel economy, abrasion resistance, wet grip performance) and processability. Various attempts have been made to improve these properties of the treads. For example, in order to improve fuel economy, abrasion resistance, and wet grip performance, it has been proposed to use a terminally modified rubber, a high molecular weight polymer, and a high glass transition temperature polymer, respectively. These methods, however, have problems such as an increase in the hardness of the rubber composition leading to deterioration of the processability. Thus, it is generally difficult to simultaneously achieve these properties.
Patent Literature 1 proposes a technique of improving fuel economy, abrasion resistance, and wet grip performance by the use of a liquid resin having a softening point of −20° C. to 45° C. and a specific silica. However, there is still room for improvement.
There has been a recent demand for further improved properties, and a need exists to achieve a further balanced improvement in fuel economy, abrasion resistance, and wet grip performance while offering good processability.